The invention claimed and disclosed herein pertains to methods and apparatus for producing images, and more particularly, to methods and apparatus for selectively producing images having increased gloss levels.
Imaging devices are in widespread use and are well known in the art. The term xe2x80x9cimaging devicexe2x80x9d includes any device that is configured to produce a visual image on an image media. Specific examples of imaging devices are printers, copiers, facsimile machines, and the like. Specific examples of image media are paper sheet, plastic film and the like.
Prior art imaging devices produce images by employing any of a number of various processes such as those known as inkjet, bubble jet, laser scanning, and the like. Each of these imaging processes is well known in the art and generally involves the deposition of an imaging substance on an image media to produce a visible image. Image substances include any substance that is configured to make up the image when deposited on the image media.
Specific examples of image substances are ink, powdered toner, and the like. An image that is produced by an imaging device is visible because of the contrast in light-reflecting characteristics between the image media and the image substance. A black image substance can be deposited on a white image media, for example, to create readable text.
Presently, one of the more popular imaging processes is that of laser scanning which is mentioned above. Imaging devices that employ the laser scanning imaging process are generally referred to as xe2x80x9claser printers,xe2x80x9d although the laser scanning process is employed in many types of imaging devices in addition to printers. The laser scanning imaging process (laser printing) generally involves selectively scanning at least one laser beam, or other light source, across an electrically charged photosensitive surface, which is generally referred to as an optical photo-conductor.
The laser is selectively scanned across the optical photo-conductor in accordance with a predetermined image which is to be produced. That is, the laser is selectively scanned across the optical photo-conductor so as to alter the relative electrical potential of respective portions thereof. The image, as a result of such scanning, is latently produced on the surface of the optical photo-conductor and is characterized by electro-statically charged portions of the optical photo-conductor as created by the selective scanning of the laser.
An imaging substance in the form of powdered toner is then applied to the surface of the optical photo-conductor. The toner generally adheres only to the selected portions of the optical photo-conductor, as created by the process of selectively scanning the laser beam across the surface of the photo-conductor. The toner that remains on the optical photo-conductor in the form of the predetermined image is ultimately transferred to an image media. The image media, along with the toner that makes up the image, is then heated in a fusing device in order to fuse the powdered toner into a plastic state. The toner then is allowed to cool, thereby becoming bonded to the media to produce the final image-product.
In addition to the above-mentioned processes, various other known processes can be employed to produce multi-color image-products such as multi-colored graphics and the like. Specifically, several toners of various colors can be employed to produce multi-colored image-products of varying quality, including near photo-quality image-products. Indeed, in some present markets, color laser printers, in combination with digital cameras and high-quality image media, are replacing traditional film processing and developing means in the photography industry.
Turning now to FIG. 1, a side-elevation schematic diagram is shown which depicts a prior art imaging apparatus 10. The prior art imaging apparatus 10 is configured to produce image-products in any of the manners generally described above. The prior art imaging device 10 comprises an in-feed tray 21 that is configured to support a stack of sheets of image media xe2x80x9cM.xe2x80x9d A pick roller 23 is positioned as shown and is configured to pick single sheets of media xe2x80x9cMxe2x80x9d from the in-feed tray 21, and to feed each sheet of media into the imaging apparatus 10. The rotational direction of the pick roller 23, as well as those of other rotating components discussed below, are indicated by the respective arrows 29.
The imaging device 10 has a print path xe2x80x9cPPxe2x80x9d which can be defined by various components of the imaging device such as feed rollers 25. The print path xe2x80x9cPPxe2x80x9d can be defined by other various components such as guides, tracks (neither shown) and the like. It is understood that the means of moving the media xe2x80x9cMxe2x80x9d through the imaging apparatus 10 and along the print path xe2x80x9cPPxe2x80x9d is well understood in the art and will not be discussed in further detail herein. The media xe2x80x9cMxe2x80x9d is generally moved through the imaging apparatus 10 in the directions indicated by the arrows 30.
The print path xe2x80x9cPPxe2x80x9d proceeds from the in-feed tray 21 and pick roller 23 through various feed rollers 25 to a deposition device 40. The deposition device 40 is configured to deposit image substance (not shown), such as toner, onto the image media xe2x80x9cMxe2x80x9d by way of any of the various imaging processes that are discussed above. For example, the deposition device 40 can be configured to employ the above-discussed laser scanning process of depositing toner onto the image media xe2x80x9cM.xe2x80x9d
If the laser scanning process is employed in conjunction with the deposition device 40, then a fusing device 50 is generally included in the apparatus 10. The fusing device 50 typically comprises a hot roller 51 and a pressure roller 52. The hot roller 51 is typically configured to convert electrical energy to heat energy. That is, the hot roller 51 typically includes a heating element or the like to produce heat.
Image media xe2x80x9cMxe2x80x9d is passed between the hot roller 51 and the pressure roller 52 during the fusing process. The pressure roller 52 is configured to press the media xe2x80x9cMxe2x80x9d against the hot roller 51 in order to optimize the amount of heat energy transferred from the hot roller 51 to the media xe2x80x9cM.xe2x80x9d The pressure roller 52 is typically not heated. However, it is understood that the pressure roller 52 can comprise a heating element so as to be heated in the manner of the hot roller 51.
Thus, at the fusing device 50, the image media xe2x80x9cM,xe2x80x9d along with the toner deposited thereon, are heated so as to fuse the toner together and bond the toner to the respective sheet of media to create a finished image-product. The image, and thus the toner, is typically directly exposed to a heat source such as the hot roller 51 during passage of the image media xe2x80x9cMxe2x80x9d through the fusing device 50.
Thus, the references made herein to the image media xe2x80x9cMxe2x80x9d and/or the image as being xe2x80x9cexposed to the fusing devicexe2x80x9d mean that the image is exposed directly to a heated object, which is usually the hot roller 51, but can be a heated pressure roller 52. The print path xe2x80x9cPPxe2x80x9d proceeds from the deposition device 40 to the fusing device 50 and on through various feed rollers 25 to an out-feed tray 22 in which the media xe2x80x9cMxe2x80x9d are deposited.
As further seen, the prior art imaging apparatus 10 can comprise an optional duplex circuit 60. The duplex circuit 60 is essentially an optional auxiliary media path that can be incorporated into an imaging apparatus and employed for duplex imaging (printing images on both sides of a given sheet of image media xe2x80x9cMxe2x80x9d). Various feed rollers 25, as well as other components such as guides, tracks (neither shown) and the like, can be included in the prior art imaging apparatus 10 for the purpose of moving sheets of media xe2x80x9cMxe2x80x9d along the duplex circuit 60 in the directions indicated by the arrows 30.
One of the primary functions of the duplex circuit 60 is to remove a given sheet of media xe2x80x9cMxe2x80x9d from the print path xe2x80x9cPPxe2x80x9d downstream of the fusing device 50 and before the sheet reaches the out-feed tray 22 after a first image (not shown) has been produced on a first side of the sheet. Another primary function of the duplex circuit 60 is to turn the sheet of media xe2x80x9cMxe2x80x9d over relative to the print path xe2x80x9cPPxe2x80x9d and the deposition device 40 so that the second side of the sheet can be exposed to the deposition device for deposition of the second image (not shown) on the second side of the sheet.
Yet another function of the duplex circuit 60 is to move the sheet of media xe2x80x9cMxe2x80x9d from the downstream side of the fusing device 50 to the upstream side of the deposition device 40, where the sheet is re-introduced to the print path xe2x80x9cPP.xe2x80x9d Thus, while the prior art duplex circuit 60 provides for exposure of a given sheet of media xe2x80x9cMxe2x80x9d to the fusing device 50 more than one time, a given image that is supported on the given sheet of media is exposed directly to the hot roller 51 not more than one time. The significance of this will become more apparent in light of the description below of the various aspects of the present invention.
A shunting device 62 can be included in the prior art imaging device 10 in order to selectively divert a given sheet of media xe2x80x9cMxe2x80x9d from the print path downstream of the fusing device 50. The shunting device 62 can be configured in any of a number of manners including that of a selectively operated diverter gate or the like. The shunting device 62 can be automatically operated by a controller (not shown) or other like device which is typically employed to control the operation of the various components of the prior art apparatus 10. Furthermore, the shunting device 62 typically includes an actuator (not shown) such as a solenoid, air cylinder or the like, that can be selectively controlled by a controller or the like.
The duplex circuit 60 typically includes a half-loop 64 that comprises a portion of the duplex circuit, as shown. The half-loop 64 causes a given sheet of image media xe2x80x9cMxe2x80x9d to turn upside down relative to the print path xe2x80x9cPPxe2x80x9d and also causes the direction of the given sheet to change by about 180 degrees. As shown in the specific example that is illustrated in FIG. 1, the half-loop 64 is configured to cause a given sheet of image media xe2x80x9cMxe2x80x9d to turn upside down as well as change its direction approximately 180 degrees relative to the print path xe2x80x9cPPxe2x80x9d so that the sheet can be moved from the downstream side of the deposition device 40 to the upstream side thereof.
Additionally, the duplex circuit 60 typically includes a reversing leg 66. The prior art apparatus 10 can also include a diverter 68 as well as a set of reversible rollers 70 which are configured to selectively and synchronously rotate in either direction as indicated by the arrows 71. The reversing leg 66, in conjunction with the diverter 68 and rollers 70, is employed to reverse the direction of the given sheet of image media xe2x80x9cMxe2x80x9d without turning the sheet upside down.
That is, as shown in the specific example that is illustrated, the given sheet of media xe2x80x9cMxe2x80x9d moves into the reversing leg 66 before stopping and completely reversing its direction with the assistance of the reversible rollers 70. As the given sheet of media xe2x80x9cMxe2x80x9d exits the reversing leg 66, the diverter 68 causes the sheet to be diverted along the duplex circuit 60 as indicated by the arrows 30 and toward the print path xe2x80x9cPP.xe2x80x9d
It is noted that the diverter 68 can be configured so as to be controllable in the general manner in which the shunting device 62 is controlled as mentioned above. More typically, however, the diverter 68 is a fully automatic self-contained device that is not controlled by a typical controller or the like. That is, the operation of the diverter device 68, in a more typical application, can be likened to that of a self-contained, automatically operating one-way check valve, or the like.
Thus, the diverter 68 can typically be configured to include a spring-loaded gate or the like that allows a given sheet of media xe2x80x9cMxe2x80x9d to enter the reversing leg 66 from a first section of the duplex circuit 60. Then, the diverter device 68 automatically diverts the given sheet of media xe2x80x9cMxe2x80x9d onto a second section of the duplex circuit 60 as the sheet exits the reversing leg.
It is understood that the relative positions of the half-loop and the reversing leg 66 can be reversed from that described above and shown in FIG. 1. That is, the reversing leg 66 and half-loop 64 can be placed on the duplex circuit 60 so that a given sheet of media xe2x80x9cM,xe2x80x9d while being moved along the duplex circuit, is first moved through the reversing leg before being moved through the half-loop.
As is evident, the given sheet of media xe2x80x9cM,xe2x80x9d once it is turned over and moved upstream of the deposition device 50, is then caused to merge onto the print path xe2x80x9cPPxe2x80x9d upstream of the deposition device 40. Once the given sheet xe2x80x9cMxe2x80x9d is back on the print path xe2x80x9cPP,xe2x80x9d the sheet moves through the deposition device 40 and a second image is deposited onto the second side of the sheet.
The sheet of media xe2x80x9cMxe2x80x9d is then moved through the fusing device 50 whereupon the second image is directly exposed to the hot roller 51 to be fused and bonded to the sheet. Once the second image is thus fused and bonded, the sheet xe2x80x9cMxe2x80x9d moves through the shunting device 62 along the print path xe2x80x9cPPxe2x80x9d and proceeds directly to the out-feed tray 22 without being withdrawn onto the duplex circuit 60.
Some prior art imaging devices are configured to selectively produce images having an increased level of finish gloss. An increased level of image finish gloss can be particularly desirable in producing high-quality graphics, and especially photo-quality images. An image comprising powdered toner can be made glossier by putting a smoother finish on the fused toner. In prior art imaging devices, such an increased level of image gloss is generally accomplished by moving the image and respective sheet of media xe2x80x9cMxe2x80x9d along the print path xe2x80x9cPPxe2x80x9d and through the fusing device 50 at reduced processing speeds.
That is, an image that is to have an increased level of finish gloss is fed along the print path xe2x80x9cPPxe2x80x9d and through the fusing device 50 more slowly than is an image that is to have a normal finish. This is generally accomplished in conjunction with prior art imaging apparatus by configuring the print path xe2x80x9cPP,xe2x80x9d and all related components thereon, such as the deposition device 40 and the fusing device 50, to have a slow speed which is utilized for producing images having increased gloss levels. For example, before a given sheet of media xe2x80x9cMxe2x80x9d receives an image that is to have an increased level of gloss, the print path xe2x80x9cPPxe2x80x9d and related components of the prior art imaging apparatus 10 are switched to slow speed.
However, before the imaging apparatus 10 is switched to slow speed, the print path xe2x80x9cPPxe2x80x9d must be xe2x80x9cflushedxe2x80x9d of imaging media. That is, before the prior art imaging apparatus 10 is switched to slow speed in anticipation of the production of a high-gloss image, the previously introduced sheets of media xe2x80x9cMxe2x80x9d which are xe2x80x9cin process,xe2x80x9d and which do not receive high-gloss images, must be completely cycled out of the print path xe2x80x9cPP.xe2x80x9d Thus, before the prior art imaging apparatus 10 is switched to slow speed for production of a high-gloss image, a given period of time must elapse in order to allow the xe2x80x9cin processxe2x80x9d sheets of media xe2x80x9cM,xe2x80x9d which are not to receive a normal image and not a high-gloss image, to complete the image-production process at normal speed.
After the prior art imaging apparatus 10 is xe2x80x9cflushedxe2x80x9d of xe2x80x9cnormal imagexe2x80x9d imaging media xe2x80x9cM,xe2x80x9d the print path xe2x80x9cPPxe2x80x9d and related components are switched to slow speed in anticipation of the production of a xe2x80x9chigh-glossxe2x80x9d image on a designated sheet of media xe2x80x9cM.xe2x80x9d The switching of the print path xe2x80x9cPPxe2x80x9d and related components to slow speed is preferably accomplished automatically in conjunction with a controller device, or the like. That is, preferably, a controller (not shown) is employed and configured to automatically switch the print path xe2x80x9cPPxe2x80x9d and related components to slow speed in response to an operator command which designates a predetermined image as a xe2x80x9chigh-glossxe2x80x9d image.
After the print path xe2x80x9cPPxe2x80x9d and related components are switched to slow speed, a selected sheet of image media xe2x80x9cMxe2x80x9d which is to receive the high-gloss image is picked from the stack of media on the in-feed tray 21. The given sheet of media xe2x80x9cMxe2x80x9d is moved along the print path xe2x80x9cPPxe2x80x9d at slow speed in the direction indicated by the arrows 30 by the respective feed rollers 25 and other various known conveying means which are not shown.
The given sheet of media xe2x80x9cMxe2x80x9d then moves through the deposition device 40 at slow speed where a given image (not shown) is deposited onto the given sheet of media. The given sheet of media xe2x80x9cMxe2x80x9d which bears the given image which is to have increased gloss then proceeds through the fusing device 50 at the slow speed. Because of the reduced operational rate, or slow speed, of the fusing device, the increased level of heat energy transferred to the image results in an increase of the finish gloss of the given image. The given sheet of media xe2x80x9cMxe2x80x9d is then moved along the remainder of the print path xe2x80x9cPPxe2x80x9d at slow speed and into the out-feed tray 22.
Alternatively, after passing through the fusing device 50, the given sheet of media xe2x80x9cMxe2x80x9d can be diverted onto the duplex circuit 60 to be moved upstream of the deposition device 40 and to be turned over. Thus, alternatively, the given sheet of media xe2x80x9cMxe2x80x9d which bears the given image can be passed again through the deposition device 40 as well as the fusing device 50 so as to bear an image on each of the sheet""s two sides.
Both of the images on the duplex sheet can be made to have increased levels of gloss in the manner described above, wherein each image is deposited and fused at the slow speed of the print path xe2x80x9cPP,xe2x80x9d the deposition device 40, and the fusing device 50. Alternatively, only one of the images on a duplex sheet can be made to have an increased level of gloss while the other image is made to have a normal level of gloss. It is noted that after a given sheet of image media xe2x80x9cM,xe2x80x9d which has had a high-gloss image produced thereon, has exited the print path xe2x80x9cPPxe2x80x9d and has been deposited on the out-feed tray 22, the prior art imaging apparatus 10 can be switched back to normal speed, and the production of images having normal levels of gloss can resume.
Turning now to FIG. 2, a flow diagram 80 is shown which depicts some of the typical steps of a prior art process for producing an image having an increased level of gloss. The process begins at step S81. The steps of the flow diagram 80 can be performed, for example, in conjunction with an imaging device such as the imaging apparatus 10 which is described above and shown in FIG. 1. With reference to both FIGS. 1 and 2, the next step of the process 80 is that of step S83, in accordance with which a sheet of media xe2x80x9cMxe2x80x9d is designated as one which is to receive a high-gloss image.
In accordance with the next step of S85, the print path xe2x80x9cPPxe2x80x9d is flushed ahead of the designated sheet of media as is described above. In accordance with the next step of S87, the processing speed of the print path xe2x80x9cPPxe2x80x9d is reduced upon completion of the flushing process. The reduction in processing speed of the print path xe2x80x9cPPxe2x80x9d includes reducing the processing speed of the deposition device 40, as well as the fusing device 50, and the various feed rollers 25 and the like.
In accordance with step S89, the designated sheet of media is fed along the print path xe2x80x9cPPxe2x80x9d at the reduced processing speed, wherein the designated sheet of media receives an image from the deposition device 40, and is exposed to the fusing device 50, both at reduced processing speed. The print path xe2x80x9cPPxe2x80x9d is then flushed upon completion of the production of the high-gloss image on the designated sheet of media, in accordance with step S91. Moving to step S93, the designated sheet of media is deposited in the out-feed tray 22. The production of images at normal processing speed resumes in accordance with step S95. The process of producing a high-gloss image ends at step S97.
As is evident from the preceding discussion, prior art imaging devices are typically configured to produce images having increased levels of gloss. However, the process employed by prior art devices for producing the increased levels of gloss comprises slowing the process speed of the entire print path xe2x80x9cPP,xe2x80x9d including the deposition device 40 and the fusing device 50. The image media and image are then passed along the print path xe2x80x9cPPxe2x80x9d and through the deposition device 40 and fusing device 50 at the slower speed. The reduced processing speed, however, can pose several problems.
One problem caused by the slower processing speed of prior art gloss processes is that the overall production rate of the imaging device 10 is also correspondingly slowed. In order to produce images having increased levels of gloss, prior art imaging devices typically must decrease overall processing speed to 33% of normal processing speed in some cases. This can cause a significant decrease in production rate of the imaging apparatus. Additionally, before the processing speed is decreased for production of the high-gloss image, the entire print path must be flushed, or cleared, of image media having images of normal gloss levels. This can cause a further decrease in the production rate of the prior art imaging apparatus 10.
Another problem associated with prior art image gloss processes is that a decrease in overall processing speed of the print path and related components such as the deposition device and fusing device can have an adverse effect on various imaging parameters such as color plane registration and the like which, in turn, can cause a decrease in image-product quality.
What are needed then are imaging apparatus and methods which achieve the benefits to be derived from similar prior art methods and/or devices, but which avoid the shortcomings and detriments individually associated therewith.
In accordance with one embodiment of the present invention, an imaging apparatus consists of a fusing device and a fusing circuit. The apparatus can also comprise a deposition device which is configured to deposit an image on a sheet of media. The fusing circuit is a media path that selectively enables an image on a given sheet of media to be repeatedly exposed to the fusing device without repeatedly passing through the deposition device. That is, the fusing circuit can cause the image to be exposed to the fusing device more than once so as to increase the finish gloss of the image, while not passing through the deposition device. The fusing circuit allows such repeated exposure of the image to the fusing device during normal processing speeds of the fusing device.
An imaging device in accordance with another embodiment of the present invention can include a fusing device having a single hot roller and a plurality of pressure rollers. For example, a fusing device of the present invention can have a single hot roller and two pressure rollers. Alternatively, a fusing device of the present invention can have a single hot roller and three pressure rollers. Any of the pressure rollers can be heated, in the alternative. Such an apparatus can further include a fusing circuit, a print path configured to convey sheets of media, and a shunting device configured to selectively divert a given sheet of media from the print path onto the fusing circuit.
In accordance with another embodiment of the present invention, a method of increasing the gloss of an image includes the steps of providing a fusing device and repeatedly exposing the image to a fusing device without passing the associated imaging media through a deposition device. As a specific example, the method can include the steps of exposing the image to the fusing device a first time and exposing the image to the fusing device a second time. The method can further increase the finish gloss of the image by the step of exposing the image to the fusing device a third time.